1. Field
The present disclosure relates generally to identifying the location and orientation of an object and, in particular, to identifying the position of a moving object. Still more particularly, the present disclosure relates to a method and apparatus for identifying the position of a moving object using images generated by the object.
2. Background
The position of an aircraft at any point in time may be defined in terms of the location of the aircraft in three-dimensional space, the orientation of the aircraft, or both the location and orientation of the aircraft. For example, the location of an aircraft may be defined by geographic coordinates and the altitude of the aircraft. The orientation of an aircraft may be defined in terms of an angle of the aircraft in relation to a given line or plane, such as the horizon. The orientation of the aircraft may be referred to as the attitude. The attitude of an aircraft may be described with reference to three degrees of freedom, referred to as roll, pitch, and yaw.
Various complex systems are employed by an aircraft to determine a current position of the aircraft. For example, the current location of an aircraft may be determined using a global positioning system (GPS). In this case, global positioning system hardware on the aircraft includes a receiver to receive signals from a number of satellites. Additional hardware and software on the aircraft determines the current location of the aircraft from the received satellite signals.
Alternatively, a radio navigation system on the aircraft may be used to determine the current location of the aircraft from radio signals received from a number of known locations on the ground. Various hardware or hardware and software systems also may be used to determine the orientation of the aircraft. For example, electromechanical gyroscope systems may be used to determine attitude of the aircraft at any point in time.
Accurate knowledge of the current position of an aircraft is desirable to effectively control the aircraft to perform a mission. However, current systems and methods for determining a position of an aircraft may affect efficient operation of the aircraft. Furthermore, current systems and methods for determining an aircraft position may not identify a current position of the aircraft as accurately as desired in different situations. For example, global positioning systems (GPS) and radio navigation systems may not be able to determine the position when signals are not available or blocked by features in the operating environment.
Accordingly, it would be advantageous to have a method and apparatus that takes into account one or more of the issues discussed above, as well as possibly other issues.